What happenes if the O2 sensor does not work in a car (other than Check Engine Light)?

Question

My corolla's O2 sensor is not working. how urgent is it to replace it?
THanks

Answer 1

It will not run as well but shouldn't cause immediate problems.

The engine management computer uses a predetermined reading to for the O2 sensor to compensate.

Your fuel mileage will decrease. If the fuel / air mixture becomes too rich for too long, you can damage your catalytic converter.

If they do emissions testing where you live, the car will fail.

I would consider having if fixed when you have the money.

Answer 2

What year of car is your (Carolla). How many miles on the car? Is the CHECK ENGINE Light on all the time? How many O2 sensors do you have? These two devices are the two most important things in keeping your car ship shape. Some cars you can move the O-2 sensors around. They need to be very hot to operate correctly. O-2 sensors are usually very reliable. If you have a diagnostic code reader on your car, it can tell you which O-2 sensor is bad via FAULT CODES. You would need to borrow a fault code reader. Install new O-2 sensors between 60K and 75K miles. They are expensive.

Answer 3

Misfires can be caused by the following in rough order of occurence combined with how easy it is to check. 1) Ignition/spk - see advice in other responses. Worn wires are not always obvious. If original '99 wires and plugs then replace just to eliminate this chance. 2) Look for air leak into manifold. There is a trick you can do by introducing propane (from torch) around engine while running at idle. In old carb days idle speed would increase if the propane was near an air leak (air from leak + fuel from propane increased speed). Modern controls seek to hold idle speed no matter what disturbances are iintroduced, but you might get a brief rise in speed or change in sound by this approach. 3) Compression too low. Run a cylinder compression test with pressure gage that costs about $10-$20. Too low indicates worn cylinders or valves that don't close or seat properly. If out of spec ask another Yahoo question on how to fix it. There are some backyard mechanic approaches but they are risky and it is best if a backyard mechanic describes how. 4) EGR too high. First verify you have EGR. Then disable EGR by plugging vacuum line. See if gets better. Then remove EGR (not easy) and clean area around valve seat. 5) Fuel too lean. -Try the injector cleaner stuff, although I can't say I have ever seen the need for it or tried it.

Answer 4

The car will continue to run, although not as smoothly. Your gas mileage will not be good and the catalytic converter will suffer. Price the converter and compare it to the O2 sensor. The sensor will be much cheaper and is DIY. I would replace it the next couple of days.

Answer 5

The O2 sensor on your car is exactly like an electronic nose.. It sits in the exhaust system trying to "sniff" out the amount of oxygen in the exhaust and sends a signal to the operating computer in your car to make fine tuning of the fuel mixture. When this sensor is not doing it's job, you risk losing power, MPG, and premature wearing of your catalytic converter and exhaust systems. If you suspect that it is not working properly, then just replace it as a matter of course. Especially if you have about 100,000 miles on your car.. They were designed to run for about this long before they wear out. Also, if you have been using cheaper fuels, (non "tier one" fuels) you will wear this unit out prematurely, as well. Good Luck!!

Answer 6

As said, it will not cause any immediate running issues.

If you are in the UK, your car will have trouble passing the MOT test without it, and doubtless other countries safety testing regimes.

One of the main purposes of the oxygen-sensor is to protect the catalytic convertor, and if lamda is not maintained at the engine, it could lead to fouling of the catalyst.

Regards,
Andy

Answer 7

Just had mine replaced last week. I don't know that it hurts anything to not replace it but my car sure was running very poorly and wouldn't want to put up with that.

Answer 8

If you want your engine to perform properly & get the best fuel mileage, fix it.If your state has emissions testing you'll need to fix it.It obviously still runs but you'll need to fix it eventually.

Answer 9

When it happened with my Camry, the engine ran very roughly, and waiting was not an option.

Answer 10

Gas mileage will suffer and maybe damage the catalytic converter.